Magnetic head and method of manufacturing a magnetic head

ABSTRACT

A slider for a magnetic head has air bearing surfaces in a medium opposing surface, and traces of processing are formed in the medium opposing surface excluding the air bearing surfaces to induce a strain in the medium opposing surface whereby the planer structure of the air bearing surfaces is controlled.

This application is a Continuation of application Ser. No. 07/952,920,filed on Sep. 28, 1992, now abandoned.

The present invention relates to a magnetic head comprising a slider anda magnetically transducing element and a method of manufacturing suchmagnetic head. More particularly, it relates to an improvement incontrolling a planar structure for an air bearing surface formed in theslider of a magnetic head.

For a magnetic disk device, there has been used a magnetic head operablekeeping an air gap between a magnetically recording/reproducing mediumand the magnetic head by utilizing a dynamic pressure produced by themovement of the medium. Such magnetic head is disclosed in, forinstance, Japanese Examined Patent Publication No. 28650/1983. As abasic construction, a magnetically transducing element is disposed atthe air-discharge end side of the slider which has an air bearingsurface at the side facing a magnetic recording/reproducing medium.

The medium opposing surface of a magnetic head of this kind is subjectedto a grinding operation so that the medium opposing surface has a highdegree of flatness. Further, it is sometime necessary to control theplanar structure of the air bearing surface to have a convex surface ora concave surface at a small local area in order to improve the startingcharacteristics and the operating characteristics. For instance, in asmall-sized magnetic disk device, there is a requirement that a sliderhas a crown structure of a slightly convexed surface so as not tosubstantially influence the flying characteristics in order to avoid anincrease of torque of the motor due to a friction by the mutual contactbetween the magnetic head and the magnetic recording medium when themagnetic disk device is started.

With respect to a technique of controlling the planar structure of theair bearing surface of slider, Japanese Examined Patent Publication No.21329/1983 discloses mechanically grinding the medium opposing surfaceof a slider. Further, Japanese Unexamined Patent Publication No.176376/1989 discloses a technique that a hardening resin is applied tothe surface opposite the medium opposing surface of a slider whereby theplanar structure of the air bearing surface is controlled by utilizingthe cure shrinkage function of the hardening resin. Further, in JapaneseUnexamined Patent Publication No. 267822/1989, there is disclosed atechnique that a groove having a relatively large width is formed in thesurface opposite the medium opposing surface to thereby control thedegree of flatness of the air bearing surface by utilizing a differenceof strain by machining between the grooved portion and the other portionwithout the groove.

However, an extremely small area is used to control the degree offlatness of the air bearing surface. For instance, a convex surfacerequired to form a crown shape has a minute convexed area in a rangefrom about 10 nm to about 300 nm. It is very difficult to form suchminute convexd area by a continuous mechanical-grinding method disclosedin Japanese Examined Patent Publication No. 21329/1983. Further, suchmechanical-grinding operation has become difficult because there is atendency of sliders being miniaturized due to a demand of low flightheight in order to perform a high density recording.

In a case of controlling flatness of an air bearing surface bycontrolling an amount of a curable resin to be attached to the slider,there is a disadvantage that the flatness of the air bearing surface ischanged due to aging of the curable resin. A method of controlling theflatness of the air bearing surface by machining a groove has such adisadvantage that it is difficult to perform the machining of a grooveand a tool for exclusive use which can provide a high flatness isrequired. Accordingly, processability was poor as a whole, andmanufacturing cost was high.

It is an object of the present invention to provide a magnetic head forsimple and reliable control, providing good processability and a lowmanufacturing cost without a change by aging in the planar structure ofthe air bearing surface, and a method of manufacturing the magnetichead.

In accordance with the present invention, there is provided a magnetichead with a slider, characterized in that the slider has an air bearingsurface in a medium opposing surface, and at least one between themedium opposing surface excluding the air bearing surface and thesurface opposite the medium opposing surface of the slider has a traceof processing which is arranged on a linear line imaginarily drawn onthe surface.

In accordance with the present invention, there is provided a method ofmanufacturing a slider with an air bearing surface in a medium opposingsurface for a magnetic head, characterized by forming a trace ofprocessing in at least one between the medium opposing surface excludingthe air bearing surface of the slider and the surface opposite themedium opposing surface of the slider, whereby the planar structure ofthe air bearing surface is controlled by a strain induced by the traceof processing.

In drawings:

FIG. 1 is a perspective view of an embodiment of the magnetic headaccording to the present invention;

FIG. 2 is an enlarged cross-sectional view partly broken taken along aline A2--A2 in FIG. 1;

FIG. 3 is an enlarged cross-sectional view partly broken of anotherembodiment of the magnetic head according to the present invention;

FIG. 4 is a perspective view of another embodiment of the magnetic headaccording to the present invention;

FIG. 5 is a perspective view of still another embodiment of the magnetichead of the present invention;

FIG. 6 is a perspective view of still another embodiment of the magnetichead of the present invention;

FIG. 7 is a perspective view of a still another embodiment of themagnetic head of the present invention;

FIG. 8 is a perspective view of a still another embodiment of themagnetic head of the present invention;

FIG. 9 is a diagram showing a relation of the number of traces ofprocessing to the planar structure of an air bearing surface; and

FIG. 10 is a diagram showing a relation of the number of traces ofprocessing to a planar structure of an air bearing surface.

Preferred embodiment of the magnetic head of the present invention willbe described with reference to the drawings. In FIGS. 1 and 2, referencenumeral 1 designates a slider and numeral 2 designates a magneticallytransducing element. The slider 1 comprises air bearing surfaces 11, 12in the medium opposing surface and a groove 13 recessed from the airbearing surfaces 11, 12. The air bearing surfaces 11, 12 is formed alongthe longitudinal direction of the slider 1. The longitudinal directionof the slider 1 coincides with an air flowing direction a when theslider 1 is placed above a magnetic recording medium such as a magneticdisk.

The groove 13 is provided with traces of processing 31-3n having a smalldepth which induce a strain in the bottom surface of the slider 1. Thetraces of processing 31-3n are formed in a direction traversing thelongitudinal direction of the slider 1, i.e. they are formed in thedirection of the width of the slider. The traces of processing 31-3n mayhave a triangle in cross section as shown in FIG. 2 or a rectangularshape in cross section as shown in FIG. 3. In the planar structure ofthe air bearing surfaces 11, 12, each of the bearing surfaces has aconvex surface which is controlled by the traces of processing 31-3n.The magnetically transducing element 2 is attached to the slider 1 at anend side in the longitudinal direction of the slider 1 which correspondsto the air flowing direction a.

The slider 1 is of a 2-rail type wherein two rails 14, 15 are formed inthe medium opposing surface so that the surfaces of the rails 14, 15 areutilized as the air bearing surfaces 11, 12. The slider 1 may have morethan two rails. The slider 1 may be of a ceramics structure such as Al₂O₃ --TiC or ferrite.

The magnetically transducing element 2 may be a thin film magnetictransducing element. In this embodiment, there is shown a thin filmmagnetic head. Numerals 21, 22 designate taking electrodes. The thinfilm magnetic transducing element 2 may be of an induction type or amagneto-resistance effect type. The induction type thin film magnetictransducing element 2 includes an in-plane recording/reproducing elementand a vertical recording reproducing element. A Winchester type magnetichead or a composite type magnetic head may be used in the presentinvention instead of the thin film magnetic head.

As described above, since the slider 1 has traces of processing 31-3n inthe groove 13 in the medium opposing surface excluding the air bearingsurfaces 11, 12, there takes place a difference of strain by processingbetween a portion where the traces of processing 31-3n are formed and aportion where there is no traces of processing 31-3n. Since the tracesof processing 31-3n are arranged on linear lines imaginarily drawn inthe bottom surface of the groove 13, there takes place a strain byprocessing so that the slider 1 is flexed at both sides of the linearlines on which the traces of processing 31-3n are formed. By the strainof processing, the flatness of each of the air bearing surfaces 11, 12of the slider 1 can be controlled. The planar structure of the airbearing surfaces 11, 12 can be controlled by suitably selecting theshape, the direction, the number, the position, the depth, and the widthof the traces of processing 31-3n even though the air bearing surfaces11, 12 have a convex surface or a concave surface. The controlling ofthe flatness of the air bearing surfaces by means of the traces ofprocessing 31-3n can be extremely easy in comparison with a case ofcontrolling the flatness of the air bearing surfaces 11, 12 by means ofdirectly grinding. Further, the planar structure can be easilycontrolled in a small area in the order of nm. Further, since the shape,the direction, the number, the position, the depth, and the width of thetraces of processing 31-3n don't change with time, there is no change ofthe planar structure of the air bearing surfaces 11, 12.

In the embodiment shown in FIGS. 1 and 2, the air bearing surfaces 11,12 and the groove 13 are formed along the longitudinal direction of theslider, and the traces of processing 31-3n are formed in the directionperpendicular to the longitudinal direction of the slider 1.Accordingly, the planar structure of the air bearing surfaces 11, 12 iscontrolled so as to have a convex surface along the longitudinaldirection of the slider 1 due to a strain of processing F1 which isresulted from the traces of processing 31-3n.

FIG. 4 is a perspective view showing another embodiment of the magnetichead according to the present invention. In FIG. 4, the same referencenumerals designate the same or corresponding parts. The traces ofprocessing 31-3n are formed along the longitudinal direction of theslider 1. By a strain induced by the traces of processing 31-3n, the airbearing surfaces 11, 12 are controlled so as to become a convex surfacealong the width direction of the slider unlike the case of FIGS. 1through 3.

FIG. 5 shows another embodiment of the magnetic head of the presentinvention, wherein the traces of processing 31-3n are formed in theopposite surface 10 which is at the opposite side of the medium opposingsurface of the slider.

If the traces of processing 31-3n are formed only in the oppositesurface 10 and they are not formed in the medium opposing surface of theslider, the air bearing surfaces 11, 12 are controlled to become aconcave surface.

When the traces of processing 31-3n are formed in the medium opposingsurface in addition to the opposite surface 10, the planar structure ofthe air bearing surfaces 11, 12 is controlled by the synthetic effect ofconvex surface formation by the traces of processing (not shown) formedin the medium opposing surface and concave surface formation by thetraces of processing 31-3n formed in the opposite surface 10. Traces ofprocessing 31-3n in the opposite surface 10 can be utilized as a way ofcorrection in a case that, for instance, there is formed excessively aconvex surface by the traces of processing in the medium opposingsurface.

The traces of processing 31-3n may be formed in the width direction ofthe slider.

FIG. 6 is a perspective view showing a still another embodiment of themagnetic head according to the present invention. In this embodiment,each of the traces of processing 31-3n is formed in a discrete manner.

FIG. 7 is a perspective view showing a still another embodiment of themagnetic head according to the present invention. The traces ofprocessing 31-3n are respectively formed obliquely with respect to thelongitudinal and width directions of the slider.

In a modification, another group of traces of processing may be formedso as to cross the traces of processing 31-3n.

FIG. 8 is a perspective view showing a still another embodiment of themagnetic head according to the present invention. The traces ofprocessing 31-3n show a spot-like distribution so as to entirely cover acertain plane area.

It is possible to suitably combine above-mentioned arrangements of thetraces of processing 31-3n although Figures are omitted. With suchcombination, the planar structure of the air bearing surface 11, 12 canbe controlled as desired.

The traces of processing 31-3n can be formed by machining the sliderwith use of a cutter or a needlelike tool made of diamond, ceramics orcarbide, or by irradiating laser, electron rays, ion beams or ultrasonicwaves to a desired portion of the slider or by injecting fine abrasiveparticles to the slider. With use of such processing traces formingmeans, the shape, the direction, the number, the position, the depth andthe width of the traces of processing 31-3n can be selected as desired.The processing operations are extremely easy, while it is possible toobtain a precise operation in the order of nm, in comparison with a casethat the air bearing surfaces 11, 12 are directly ground to control theplanar structure of the bearing surfaces.

FIGS. 9 and 10 are respectively observed data showing relations of thenumber of traces of processing to degrees of controlling the planarstructure of the air bearing surfaces wherein the abscissa representsthe number of traces of processing and the ordinate represents PV values(nm) measured to the air bearing surfaces. These data were obtained byusing the magnetic head shown in FIGS. 1 through 3.

FIG. 9 shows data obtained by forming traces of processing having alength of 600 μm and a pitch of 200 μm with use of a diamond tool havingan edge angle of 120° to which a load of 100 gr is applied. FIG. 10shows data obtained by forming traces of processing having a length of700 μm and a pitch of 100 μm with use of a diamond tool having an edgeangle of 120° to which a load of 150 gr is applied.

It is found from the data that the PV value can be controlled dependingon the depth and the width of the traces of processing (which is reliedon a load) the number, the length and the pitch of the traces ofprocessing.

In accordance with the present invention, the following advantages canbe obtained.

(a) The slider is provided with traces of processing on at least onebetween the medium opposing surface excluding the air bearing surfacesand the surface which is opposite the medium opposing surface, thetraces of opposing being formed on linear lines imaginarily drawn onsuch surface or surfaces. Accordingly, there can be provided a magnetichead capable of controlling the flatness of the air bearing surfaces ofthe slider by utilizing a difference of strain caused between a portionhaving the traces of processing and a portion without traces ofprocessing.

(b) There can be provided a magnetic head which is highly flexible inselecting the planar structure of the air bearing surfaces, namely, theair bearing surfaces having a convex surface or a concave surface can beobtained by suitably selecting the direction, the number, the position,the depth, the width and the shape of the traces of processing.

(c) There can be provided a magnetic head which can easily control theplanar structure of the air bearing surfaces in comparison with a casethat the air bearing surfaces are directly ground, and which can easilycontrol the planar structure of the air bearing surfaces in a small arearange in the order of nm.

(d) Since the direction, the number, the position, the depth and thewidth of the traces of processing are not changed with a lapse of time,there can be provided a magnetic head free from a change in the planarstructure of the air bearing surfaces due to change with time.

(e) Since the traces of processing are formed by mechanically processingthe slider with use of a cutter or a needle-like tool made of diamond,ceramics or carbide, or by irradiating laser, electronic rays, ion beamsor ultrasonic waves to a necessary portion of the slider, or byinjecting fine abrasive particles to the slider, there can be provided amethod of manufacturing a magnetic head which allows to select thenumber, the position, the depth, the width and the shape of the tracesof processing, can easily process the slider in comparison with a casethat the air bearing surfaces of the slider are directly ground tocontrol the planar structure, and can control processing as precise as asmall area range in the order of nm.

What is claimed is:
 1. A magnetic head with a slider, wherein saidslider has at least two air bearing surfaces in a medium opposingsurface, said slider also having a surface remote from the mediumopposing surface, said slider having at least one trace of processing,said trace of processing arranged on a linear line imaginarily drawn ona groove between the air bearing surfaces, said trace of processingformed by a process selected from machining, irradiating laser, electronrays, ion beams, or ultrasonic waves, or by injecting fine abrasiveparticles to the slider, so that said trace induces a strain in thegroove between the air bearing surfaces, said strain controlling thedegree of flatness of the air bearing surfaces, wherein said air bearingsurfaces are either all convex or all concave.
 2. The magnetic headaccording to claim 1, wherein two air bearing surfaces are arranged witha space in the longitudinal direction of the slider, and the at leastone trace of processing is provided in the medium opposing surfacebetween the air bearing surfaces.
 3. The magnetic head according toclaim 1, wherein the at least one trace of processing are in the form ofstripes.
 4. The magnetic head according to claim 1, wherein the at leastone trace of processing are discretely formed.
 5. The magnetic headaccording to claim 1, wherein the slider is provided with a magneticallytransducing element at an end side in its longitudinal direction, andthe at least one trace of processing are formed in the directiontraversing the longitudinal direction of the slider.
 6. The magnetichead according to claim 5, wherein the at least one trace of processingis formed obliquely with respect to the longitudinal and widthdirections of the slider.
 7. The magnetic head according to claim 1,wherein the slider is provided with a magnetically transducing elementat an end side in its longitudinal direction, and the at least one traceof processing are formed along the longitudinal direction.
 8. Themagnetic head according to claim 1, wherein the slider has more than twotraces of processing which are provided with intervals.
 9. The magnetichead according to claim 1, wherein said process is machining with acutter or needle tool.
 10. The magnetic head according to claim 1,wherein said process is selected from irradiating laser, electron rays,ion beams, or ultrasonic waves, or by injecting fine abrasive particlesto the slider.
 11. The magnetic head according to claim 1, wherein saidat least one trace of processing has a triangular shape in crosssection.
 12. The magnetic head according to claim 1, wherein said atleast one trace of processing has a rectangular shape in cross section.13. The magnetic head according to claim 1, wherein said slider is madeof a ceramic.
 14. The magnetic head according to claim 1, having atleast one trace of processing in said medium opposing surface and atleast one trace of processing in said surface remote from said mediumopposing surface, whereby the planar structure of said air bearingsurfaces is controlled by the effect of convex surface formation by saidat least one trace of processing formed in the medium opposing surfaceand a concave surface formation by said at least one trace of processingformed in said surface remote from said medium opposing surface.